President Trump on Monday ordered Singapore-based Broadcom to abandon its $117 billion hostile bid for Qualcomm, blocking what would have been one of the biggest technology deals in history.

In his presidential order, Trump cited “credible evidence” that the takeover “threatens to impair the national security of the United States.” The merger would have put one of America’s largest mobile chipmakers in the hands of a company based in Asia, a region that has been racing against American companies to develop the next generation of mobile technology.

The administration moved with unusual speed in the matter that caught many involved in the negotiations off guard. The Committee on Foreign Investment in the United States, or CFIUS, an interagency panel led by the Treasury Department, had several more weeks to render a recommendation to the president. Trump's order cannot be appealed, legal experts said.

The move demonstrates the high value that the administration places on maintaining the U.S. edge in developing micro technologies.

The administration did not detail its national security concerns, but CFIUS last week sent a letter to the attorneys of the two companies saying it was concerned research and development at Qualcomm might atrophy under Broadcom's direction, according to a copy that was reviewed by The Washington Post. If that happened, China's Huawei Technologies, a rival to Qualcomm and a major producer of mobile chips, might become much more dominant around the world.

The tiny computer chips embedded in smartphones, smart home gadgets, and a wide range of other connected devices are expected to become one of the most critical technologies in coming years. These chipsets enable connected cars to speak to each other as well as stoplights. Almost every major business and consumer electronics manufacturer uses Qualcomm's technology as brains for their devices.

Trump's order is in keeping with the administration's protectionist instincts. Last week, Trump also cited national security concerns in announcing harsh tariffs on steel and aluminum imports, a move that hit rivals such as China as well as allies such as Germany and South Korea. Several other technology deals fell apart, after CFIUS raised concerns. In September, Trump stopped the $1.3 billion acquisition of Portland-based Lattice Semiconductor by a private-equity firm that had close ties to Beijing.

One factor that may have pushed CFIUS to move quickly was an unusual maneuver by Broadcom to relocate to the United States. The company had said in a recent corporate filing that it was finalizing its plans to become an American entity in early April. Deals between American companies fall out of CFIUS's jurisdiction.

A person familiar with CFIUS's investigation, who spoke on the condition of anonymity to freely discuss the matter, said this strategy may have doomed the transaction. “If there is one lesson here, it’s don’t screw with the government,” the person said.

He described Trump’s executive order as “brutal.” “It smacks of anger on the part of the government to me. This feels a little more personal to me.”

Qualcomm said in a statement that it received the order, which required the company to reconvene its annual shareholder meeting on the earliest possible date following a notice period. The meeting will take place March 23, the company said. Broadcom, in a statement, said it was reviewing the order and “strongly disagrees that its proposed acquisition of Qualcomm raises any national security concerns.” In after hours trading, shares of Qualcomm sunk as much as 4 percent from its market close of $62.81. Shares of Broadcom rose less than 1 percent.

Qualcomm and a host of other big technology companies are racing to build a next-generation nationwide network. known as "5G,” with download speeds that could be 100 times as fast as what most consumers experience now on their wireless service. Once deployed, a high-definition movie could load instantly on a smartphone. The capabilities of connected devices at work and home would vastly expand. Cable-quality service could even be provided over the air, instead of a wireline connected to a house.

Several analysts said the U.S. government is growing concerned that Huawei will develop such technologies almost as fast as their American counterparts, narrowing the gap between Chinese and U.S. companies.

But Rod Hunter, a partner at Baker McKenzie and a former senior director for international economics at the National Security Council, said it is not clear what exactly prompted CFIUS, a notoriously secret government body, to act so quickly.

Hunter said it could reflect “an evolution in the thinking” of the committee, perhaps an indication that it’s going to approach transactions in which foreign people or entities seek to own 5G wireless technology with the same sensitivity and rigor that the feds “apply to military equipment traditionally.”

“Typically when you’re doing these CFIUS cases, you look at what the business is and how sensitive it is,” Hunter said. “If it’s a Chinese investor, the bar is going to be high. A Singaporean investor you would not normally have considered a high risk.”

Updated with statement from Qualcomm.

Tony Romm contributed to this report.

Hamza ShabanHamza Shaban is a technology reporter for The Washington Post. Previously, he covered tech policy for BuzzFeed. Follow